This code prepares the spatial data for the Gulf of California region. For the equal area projections, I will use Albers Equal Area EPSG:5070

Area of the GoC: 179,938 km2 (177,000 km2 according to Wikipedia)

STEP 1 Obtain high resolution polygon of Gulf of California region

Open Street Map seemed to have the highest resolution coastline data. Data downloaded from here (Dec 18 2024): https://osmdata.openstreetmap.de/data/water-polygons.html

Combined with data from: https://www.marineregions.org/downloads.php to get border data.

STEP 2 Make some decisions

Question 1: Should we follow the Gulf of California boundary? Or, should we follow the Ecoregion boundary?

Boundary 1: Ecoregion

## Reading layer `water_polygons' from data source 
##   `/home/shares/ohi/OHI_GOC/spatial/water-polygons-split-4326/water_polygons.shp' 
##   using driver `ESRI Shapefile'
## Simple feature collection with 53357 features and 2 fields
## Geometry type: POLYGON
## Dimension:     XY
## Bounding box:  xmin: -180 ymin: -78.73859 xmax: 180 ymax: 90
## Geodetic CRS:  WGS 84
## Deleting layer `GoC_polygon_ecoregion_latlon' using driver `ESRI Shapefile'
## Writing layer `GoC_polygon_ecoregion_latlon' to data source 
##   `/home/frazier/ohi_goc_prep/spatial/GoC_polygon_ecoregion_latlon.shp' using driver `ESRI Shapefile'
## Writing 1 features with 0 fields and geometry type Polygon.
## Deleting layer `GoC_polygon_ecoregion_eqarea' using driver `ESRI Shapefile'
## Writing layer `GoC_polygon_ecoregion_eqarea' to data source 
##   `/home/frazier/ohi_goc_prep/spatial/GoC_polygon_ecoregion_eqarea.shp' using driver `ESRI Shapefile'
## Writing 1 features with 0 fields and geometry type Polygon.

Boundary 2: Sea of Cortez boundary

## Deleting layer `GoC_polygon_sea_latlon' using driver `ESRI Shapefile'
## Writing layer `GoC_polygon_sea_latlon' to data source 
##   `/home/frazier/ohi_goc_prep/spatial/GoC_polygon_sea_latlon.shp' using driver `ESRI Shapefile'
## Writing 1 features with 0 fields and geometry type Polygon.
## Deleting layer `GoC_polygon_sea_eqarea' using driver `ESRI Shapefile'
## Writing layer `GoC_polygon_sea_eqarea' to data source 
##   `/home/frazier/ohi_goc_prep/spatial/GoC_polygon_sea_eqarea.shp' using driver `ESRI Shapefile'
## Writing 1 features with 0 fields and geometry type Polygon.
## |---------|---------|---------|---------|=========================================                                          
## |---------|---------|---------|---------|=========================================

Question 2: Should we include subregions?

Should we have one OHI score that represents the entire region? We can make further divisions according to ecoregions, estados, etc. The region is fairly small, so I’m not convinced subdivision makes sense.

This image provides estados and ecoregions boundaries:

This image provides ecoregion boundaries: This image provides a useful view of the primary river inputs (for reference):

Other resources

Watersheds: https://databasin.org/datasets/5637f67d31d94a1cb165cdbddb8c4257/ /home/shares/ohi/OHI_GOC/spatial/Major Watersheds of Mexico